Having similar experience, I used to deal with the best people at their worse and the worst people at their best. After 10 yrs, I took a different career path that involved extended travel and full timing followed suit. Due to the nature of travel, government parks have been my choice with an occasional monthly stay at a small commercial RV park. Fortunately, I've never had anything taken from my campsite in all the years I've camped.
Only once, did I have a slight issue. I was the only RV in a small city park, when someone decided to go through one of my outside compartments while I was inside having lunch. Why the person disregarded the tell-tale signs that I was home, I'll never know. A couple of friends of mine and I went out to see what all the commotion was. The homeless gentleman quickly concluded that it was in his best interest to move on. I notified authorities by phone with a description, placed the misc. items back into the compartment and locked the door, which simply keeps a relatively honest person honest.